The measurement of thin films and coatings is appreciated in manufacturing settings. For example, regulating the application of a thin film or coating to a product within a preferred thickness range allows manufacturers to ensure that a film or coating is applied with sufficient thickness to prevent manufacturing defects while also avoiding wasteful application of film or coating in excess of a required thickness, thereby minimizing materials costs. In the context of manufacturing processes, measurement of thin layers of lubricious coatings on metals allows manufacturers to ensure that sufficient coating is applied to prevent substantial damage to expensive manufacturing and processing equipment. Furthermore, it is preferable to periodically perform measurements of thin films or coatings in real-time as the films or coatings are applied before the coated substrate proceeds further through the manufacturing process.
There are several currently known techniques for measuring thin films or coatings. However, the known methods have various limitations that significantly undermine their respective usefulness in industrial applications. For example, standard reflectometry based measurement techniques become unreliable when the thickness of the subject coating/film under consideration is below 200 nanometers (1 nanometer=0.001 microns). Known modeling-based reflectometry techniques are not well-suited and not robust enough for use in industrial production environments.
In addition, modeling-based reflectometry techniques for measuring film or coating thicknesses of less than 0.2 microns have typically focused on measurement of coatings and films on semiconductor substrates. However, applications of coatings or films in the semiconductor manufacturing process are performed on static (non-moving) substrates. A significant limitation of the currently known modeling-based reflectometry techniques capable of measuring coatings of less than 0.2 microns is that they require a static substrate on which to perform measurements of coatings or materials deposited thereon.
The present disclosure is directed to methods and systems for real-time in-process measurement of thin films or coatings, including films or coatings of less than 0.2 microns, on a moving substrate, and therefore overcomes the limitations of known methods and systems.